Increasingly, there is a need for a carrier network architecture capable of providing a variety of communication services, for example, ranging from voice grade telephone service to packet switched data services and broadband digital communications services. Modern society continues to create exponentially increasing demands for communication of various forms of information. Desired services now range from simple text and voice communications up through broadband communications for video and multimedia applications.
The existing telephone network has fostered much of this growth. However, the current architecture of that network, essentially designed in the 1960s, uses time division multiplex technology optimized for voice grade telephone services. Although many users are satisfied with the services of such a network, increasingly many customers are exploring competing options for obtaining communication services that involve much higher-rate digital communications. Consequently, telephone carriers are faced with a need to migrate the existing services up to a higher capacity network that will support those services as well as the newer broadband digital services demanded by sophisticated customers. These trends are forcing telephone service carriers to migrate to a fast packet network architecture supporting broadband services. Existing end office switches simply cannot handle broadband services and are not readily adaptable to the fast packet operations. A number of proposals have been suggested to upgrade or replace the telephone network, to provide the newer types of services.
For example, U.S. Pat. No. 5,864,415 to Williams et al. discloses a fiber-to-the-home network architecture. Optical fiber extends from the central office to an intelligent interface device within the home. The intelligent interface device provides interconnections to various analog and digital communication media within the home, including a telephone line and a data network (10BaseT cable). The Williams patent also suggests use of a ring architecture, for the higher-level portions of the network.
U.S. Pat. No. 5,541,917 to Robert D. Farris discloses an advanced intelligent network type communication system, which provides both telephone service and broadband service. The disclosed architecture includes service switching point (SSP) type telephone central offices, signaling transfer points (STPs) and a central controller implemented as an integrated service control point (ISCP). At least some services are provided via SSP type host digital terminals (HDTs) and/or asynchronous transfer mode (ATM) type SSP switches. The HDT, for example, communicates via optical fiber to optical network units (ONUs) at the curb-side, and it communicates with higher level elements of the network via fiber.
Recent proposals for fiber optic metro area networks, such as that described in the white paper: Sistanizadeh, “Managed IP Optical Internetworking, a Regional IP-over-Fiber Network Service Architecture,” © 2000 Yipes Communications, Inc., suggest a multi-layered optical fiber ring network. A first level ring connects Ethernet switches that provide access for customer equipment to Ethernet switches in the distribution plane. A next level ring connects a number of the distribution switches, and this ring connects to a switch at a hub on the national ring network.
While these proposals for network architecture separately address some of the needs of the carrier, such as the incumbent local exchange carrier, from that carrier's perspective, each has certain shortcomings. For example, many of the more recent proposals, such as that by Sistanizadeh, have emphasized handling of broadband data traffic. Although these proposals envision carrying voice (e.g. as voice over IP traffic), they have not adequately addressed issues regarding service control, particularly in such a manner as to enable seamless migration of the wide range of existing telephone services from the old TDM switch network up to the newly proposed packet or ATM based network. Consequently, they have not really addressed issues of serving both newer broadband based applications as well as legacy telephone applications, which many telephone customers will continue to demand (and pay for) for many years to come.
Also several U.S. pre-grant patent publications to Benedyk et al. (US2001/0055380), Sugiyama et al. (US2001/0024438) and Suzuki (US2001/0027983) disclose proposals for using media gateways to interface time division multiplexing (TDM) based telephone equipment to IP-based wide area data networks. These documents also teach control of telephone service through the media gateways at least in part by control functionality provided by one or more media gateway controllers. These architectures apparently are intended as a migration or partial upgrade strategy for the existing telephone carriers. In a somewhat similar vein, Telica (of Marlboro, Mass.) offers a system for interfacing older telephone switches to an IP-based backbone network. Telica proposes a network architecture in which a specialized gateway device interfaces telephone calls and other communications to and from a packet data core network. Although the functions may be integrated in a single device or ‘box’ having both switching fabric and service logic, they have also suggested the possibility of a more distributed implementation. These proposals have focused on enhanced transport in higher levels of the network. Although such an approach alleviates congestion at the tandem level, that approach does not address issues relating to broadband service transport through levels beyond the backbone. The broadband services do not consistently extend to and through the last mile to the actual customer premises.
Hence a continuing need exists for a network architecture and elements thereof that will efficiently provide a combination of broadband services and telephone services, which will enable a carrier to continue to support existing telephone services as well as meet demands for ever greater digital bandwidth for newer broadband applications out to the network edge. A related need exists for such a network to seamlessly support telephone applications, whether for newer customers serviced through the enhanced broadband elements of the network or for customers accessing the network through remaining legacy equipment.